[Backend][Info] WebSocket session polls not cleaned up when session is killed

[OneStepAt4time]

Summary

ws-terminal.ts:95-103,190-200 — sessionPolls entries are cleaned up when all WebSocket subscribers disconnect. However, if a session is killed via the API, existing subscribers are not notified and the shared poll timer continues calling tmux.capturePane on a non-existent window, failing silently forever.

Files Affected

• src/ws-terminal.ts:95-103, 190-200

Suggested Fix

When a session is killed, actively close all WebSocket connections for that session and clean up the poll entry. Or have the poll detect session death and self-terminate.

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Code review finding from full codebase audit (2026-04-04)

[OneStepAt4time]

Closing per decisione Ema.